fix axes to be at midpoint of vertices

Author: krVatsal

editor/src/messages/tool/tool_messages/path_tool.rs

@@ -590,6 +590,7 @@ struct PathToolData {
 	last_clicked_point_was_selected: bool,
 	last_clicked_segment_was_selected: bool,
 	snapping_axis: Option<Axis>,
+	snap_axis_origin: Option<DVec2>,
 	alt_clicked_on_anchor: bool,
 	alt_dragging_from_anchor: bool,
 	angle_locked: bool,
@@ -1974,7 +1975,7 @@ impl Fsm for PathToolFsmState {
 						// Draw the snapping axis lines
 						if tool_data.snapping_axis.is_some() {
 							let Some(axis) = tool_data.snapping_axis else { return self };
-							let origin = tool_data.snap_manager.indicator_pos().unwrap_or(tool_data.drag_start_pos);
+							let origin = tool_data.snap_axis_origin.or_else(|| tool_data.snap_manager.indicator_pos()).unwrap_or(tool_data.drag_start_pos);
 							let viewport_diagonal = viewport.size().into_dvec2().length();
 
 							let faded = |color: &str| {
@@ -2124,16 +2125,35 @@ impl Fsm for PathToolFsmState {
 				{
 					// Constrain molding to a single axis when Shift is held
 					let mouse_position = if snap_axis_state {
-						let delta = input.mouse.position - tool_data.drag_start_pos;
+						// Calculate the midpoint between the segment's two anchor endpoints for the axis overlay
+						let midpoint = if let Some(vector) = document.network_interface.compute_modified_vector(segment.layer()) {
+							let transform = document.metadata().transform_to_viewport(segment.layer());
+							let points = segment.points();
+							let pos1 = vector.point_domain.position_from_id(points[0]);
+							let pos2 = vector.point_domain.position_from_id(points[1]);
+							if let (Some(p1), Some(p2)) = (pos1, pos2) {
+								(transform.transform_point2(p1) + transform.transform_point2(p2)) / 2.0
+							} else {
+								tool_data.drag_start_pos
+							}
+						} else {
+							tool_data.drag_start_pos
+						};
+						tool_data.snap_axis_origin = Some(midpoint);
+
+						// Constrain mouse movement relative to drag start so molding delta stays correct
+						let drag_start = tool_data.drag_start_pos;
+						let delta = input.mouse.position - drag_start;
 						let axis = if delta.x.abs() >= delta.y.abs() { Axis::X } else { Axis::Y };
 						tool_data.snapping_axis = Some(axis);
 						match axis {
-							Axis::X => DVec2::new(input.mouse.position.x, tool_data.drag_start_pos.y),
-							Axis::Y => DVec2::new(tool_data.drag_start_pos.x, input.mouse.position.y),
+							Axis::X => DVec2::new(input.mouse.position.x, drag_start.y),
+							Axis::Y => DVec2::new(drag_start.x, input.mouse.position.y),
 							_ => input.mouse.position,
 						}
 					} else {
 						tool_data.snapping_axis = None;
+						tool_data.snap_axis_origin = None;
 						input.mouse.position
 					};
 
@@ -2397,6 +2417,7 @@ impl Fsm for PathToolFsmState {
 				tool_data.temporary_adjacent_handles_while_molding = None;
 				tool_data.angle_locked = false;
 				tool_data.snapping_axis = None;
+				tool_data.snap_axis_origin = None;
 				responses.add(DocumentMessage::AbortTransaction);
 				tool_data.snap_manager.cleanup(responses);
 				PathToolFsmState::Ready
@@ -2645,6 +2666,7 @@ impl Fsm for PathToolFsmState {
 				}
 
 				tool_data.snapping_axis = None;
+				tool_data.snap_axis_origin = None;
 				tool_data.sliding_point_info = None;
 
 				if drag_occurred || extend_selection {